Lathe adapter



my 2, w46. H C, GRAEBE 2,403,175

` LATHE ADAPTER Filed July 9, 1945 2 Sheets-Sheet l /7 'l Herman E Eraehg July 2, 1946.

H. C. GRAEBE LATHE ADAPTER 2 sheetssheet 2 Filed July 9, 1943 Herman EE'raEhE @3M @am www Patented July 2, 1946 LATHE ADAPTER Herman C. Graebe, Bridgewater, Mass., assignor to Carver Cotton Gin Company, Division of The Murray Company, East Bridgewater, Mass., a

corporation of Texas Application July 9, 1943, Serial No. 494,057

4 Claims. l

'I'his invention relates to an apparatus for converting lathes of comparatively short length of bed to perform deep hole drilling.

The drilling of deep holes in any object, and especially gun barrel tubes, is generally performed on special boring equipment. Such equipment is provided with a long bed to accommodate the full rearward travel of the boring bar as itis withdrawn after completion of the drilling to clear the end of the workpiece. Further, specialized boring equipment is generally provided with rather complicated electrical devices for the operations of feeding and retracting the boring mechanism. In addition electrically controlled safety devices are provided to prevent breakage of the drill.

For the small shop which cannot afford to procure such equipment or even when the procurement of specialized boring machinery is not feasible due to the stress of wartimes, it becomes necessary to utilize existing equipment. There are frequently found in such small shops lathes having a comparatively short bed that can conveniently accommodate the long gun barrel yet would not permit full travel of the carriage for drilling the bore in one continuous operation. If such lathes could be adapted to bore long tubular members, such as a gun barrel, considerable additional work could be undertaken with existing equipment.

Accordingly it is an object of this invention to provide a lathe adapter for converting a lathe having a comparatively short bed to permit deep hole drilling by advancing the drill into the workpiece by steps.

Another object of this invention is to provide an oil coupling for the boring bar of a lathe adapter for lubrication and for washing away such chips as are formed by the drilling.

A particular object of this invention is to provide a lathe adapter having a mechanical safety device to prevent damage to a deep hole drill.

The specic nature of the invention as Well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a front elevational view showing the adapter mounted on the bed of a lathe.

Fig. 2 is an enlarged view showing the oil cou pling in longitudinal section mounted on the end of the boring bar and also the safety device shown partly in longitudinal section.

Fig. 3 is an enlarged longitudinal sectional view of the cats head or rotating end support.

Fig. 4 is an enlarged left end view of the safety device as Viewed in Fig. 2 shown partly in section.

Fig. 5 is an'enlarged front elevational View of the safety device.

Fig. 6 is an enlarged end elevational view of the safety device bracket.

Fig. 7 is a right side elevational view of Fig. 6.

Fig.'8 is a top elevational view of the clamp.

Fig. 9 is a top end relevational View of Fig. 8.

Fig. 10 is a left end elevational view of the clamp holder as viewed in Fig. 2.

Fig. 11 is a side elevational view of Fig. 10.

Fig. 12 is a top elevational View of the clamp holder lever showing the eccentric lug on one end thereof.

This invention utilizes conventional lathe equipment for deep hole drilling and employs a drill clamping device which can be mounted on the carriage of the lathe and may beadjusted to clamp the drill in any position desired. For example, after the boring has progressed a short distance into a barrel tube the boring may be stopped, the device unclamped and the Vdrillengaged in a new position so that the boring may progress to a greater depth. In thismanner a lathe having .a comparatively short bed may be readily utilized.

Av simple mechanical safety to prevent injury to the drill is also provided on the drill clamping device which will immediately unclamp the drill and permit it to rotate with the barrel tube in the event the drill sticks Within the bore.

There is shown in Fig. 1 a portion of a conventional lathe bed l on which is mounted the adapter for deep hole drilling. It is desired toV point out that rthe adapter to be described herein may be utilized for deep hole drilling in any object which can be mounted in the lathe. A gun tube of a comparatively large caliber gun is one eX- ample where deep hole drilling'must be utilized and will serve to illustrate the manner in which this attachment can be utilized. In most deep hole drilling operations the drill is held stationary while the gun tube is revolved and the drill is advanced into the work. Accordingly Va chuck 2 conventionally mounted on the headstock of the lathe (not shown) is utilized to drive a gun tube 3 while drilling the hole. Y

The conventional carriage 4 of the lathe as well as the traversing mechanism 1s also utilized; A live end rest 5'(Figs. 1 and 3) is provided and is mounted on the ways of the lathe bedl between th'e headstock 2 and the carriage 4. The end resti comprises a bearing support 6 in which is rotatably mounted a cats head or rotating end support 1. The bearing support 6 comprises a base 8 and a cylindrical head 9. An axial hole I is provided in the cylindrical head 9 in which the cats head 1 is inserted. The cats head 1 comprises a hollowcylindrical head portion ||v and an integral spindle l2. A axial hole I3 is provided in spindle l2. The end of hole I3 1n spindle |2 adjacent the hollow cylindrical head II is counterbored slightly to receive a flanged bushing I4. Bushing I4 is secured to the inte-n rior of head by a pin I5 toprevent rotation thereof. An axial hole |6 is provided in bushing |4 which serves to guide a drill which istobe described. Four equally spaced adjusting screws I1 are provided about the periphery of the head II.

A rod carrier |8 (Figs. l and 2) is mounted on top of the compound rest of carriage 4 in place of the usual tool post. The carrier I8 comprises a bracket I9 (Figs. 6 and '1 to which is secured the safety device and clamping mechanism to be described. Bracket I 9 comprises a horizontal cylindrical head 2|] and an integral I J-shaped support 2|. On the bottom of support 2| integral lugs 22 are provided for mounting the bracketY I9 on top of the compound rest of the carriage. Two suitable holes 23 are provided in the base of the U-shaped support 2| in which two bolts 24 are inserted to secure bracket I9 to the ccmpound rest in place of the toolpost holder.

A release pin bracket 25 isbolted to an integral upright lug 26 provided on the left arm of the U-shaped support 2| as viewed in Fig. 2. The bracket 25 (Figs. 2, 4 and 5) comprises a base 21 and an integral cylindrical portion 28 in the center thereof. An arm 29 projects outwardly from th'e base 21. An integral lug 29a is provided on the end of arm 29 and is disposed at an angle to the arm 29 as shown in Figs. 4 and 5. An adjustable stop 30 which comprises a bolt and lock nut 38 is screwed in to a suitably threaded hole in the lug 29a. Two holes 3| are provided in base 21 so that bolts 32 may be inserted therein and screwed into suitably threaded holes in the lug 26 to secure the bracket 25 to the bracket 9. Thus' when bracket 25 is mounted on bracket I9 the cylindrical portion 28 of thebracket 25 will bein aA horizontal position and thearm 29 will project upwardly over the cylindrical portion 28. An axial counterbored hole 33 is provided in cylindrical portion 28 of bracket 25 in which' is inserted a plunger 34. Plunger 34 is provided with an integral flange 35 on the inner end thereof, said flange abutting the bottom of counterbored hole 33, the inner end portion of plunger 34 projecting through hole 33 slightly beyond the face of the end of cylindrical portion 28 and being preferably wedge-shaped. A nut 31 is screwed into the threaded counterbored end 38 of hole 33 to retain a spring 39 therein. A set screw 4|] is provided througn the cylindrical portion 28 which bears against the nut 31 to prevent nut 31 from being displaced.

An axial hole 4I (Fig. 6) is provided in the cylindrical head 20 of bracket I9 to receive a clamp holder 42 (Fig. 1l). The clamp holder 42 comprises a tubular portion 43 having a cylindrical head 44 on one end. The other end of the tubular portion 43 is threaded to receive a nut 14 (Fig. 2). An axial hole 46 is providedrin the clamp holder V42 to receive a drill rod 41 (Fig. 2) A V- shaped notch 48 corresponding to the wedgeshaped end of plunger 34 is provided on the outer surface of the cylindrical head 44 of clamp holder 42. An integral lug 49 is provided on the face of the cylindrical head 44. Lug 49 is substantially rectangular in form but is provided with one rounded end concentric with the axis of the axial hole 45. One corner 50 in lug 49 is located on the vertical axis of the clamp holder 42 as shown in Fig. l0. A hole'5| is provided in the corner 50 of the lug 49. The lug 49 is also cut Yaway as shown in Fig. l0 to form a shoulder 52. A circular end mill cut is made on the face of lug 49 to form an oblique slot 53 as shown in Fig.

10 which extends to the center of hole 46.

Clamp holder l42 is inserted in the axial hole 4| of bracket I9 in such fashion that V-shaped notch.43 will be opposite the release plunger 34 supported in bracket 25. A clamp 54 (Figs. 8 and 9) is inserted in the slot 53 of clamp holder 42.. Clamp 54 is a rectangular member provided with a rounded end 55 tofit the end of slot 53. A transverse hole 55 connected with a longitudinal slot 51 is provided for clamping the drill rod 41.

A lever 58 is pivotally mounted on the upper corner of lug 49 by a pin 59 inserted through a suitable hole in lever 5B and into hole 5|. -A set screw 60 inserted in threaded hole 8| in the hub 82 of lever 58 bears against a suitable flat portion on pin 59 and securely locks lever 58 to pin 59. The hub 62 of lever 58 is generally rounded but includes an eccentric surface portion 83. The eccentric surface 63 bears 'against the side of clamp 54 when lever 58 is pivoted in a clockwise direction as viewed in Fig. 4 to tighten clamp 54 about the drill 41.

In the lower corner of lug 49 a threaded hole 64 is provided in which is inserted an adjusting bolt 65. A lock nut 66 is provided on bolt 65 to lock bolt 65 in any desired position. A bent pin 61 is inserted in a suitable vertical hole in lever pin 59'. An annular groove 68 is provided in the bent portion of pin 61 to receive one end of spring 69. A cover 10 of the Vsame conguration as lug 49 is placed on top of lug 49 to retain clamp 54 and lever 58 in their respective positions. Cover 10 is secured to lug 49 by three bolts 1|. The lower end of spring 89 is secured to a screw 12 inserted in a threaded hole 13 in cover 10. A circular nut 14 is screwed on'to the threaded end of clamp holder 42 and is locked thereon by a bolt 15 inserted through a suitably threaded hole in nut 14 and screwed into engagement with the threaded end portion of clamp holder 4?.A

The drill rod 51 utilized is a conventional single lip drill used for deep hole boring and comprises a single lip boring bit 16 and a boring bar 41 (Fig. 3). An axial hole 11 is provided in boring bar and bit so that oil under pressure may be forced to the cutting end of drill 16 for lubrication and also to wash chips out of the hole being bored so that the drill will not bind in the bore. An oil coupling 18 is provided on end of bar 41. Coupling 18 comprises a circular cylindrical casting 19 which is provided with an axial hole 8| so that the coupling may be slipped over the end of boring bar 41. The hole 8| is suitably counterbored at each end to receive oil tight packings 82 and bushings 83 respectively.- The coupling 18 is held in position on the end of boring bar 41 by two collars 84 suitably secured to bar 41 placed adjacent each bushing 83. A suitable oil tight fitting 85 (Fig. 1) is inserted in a centrally located radial hole 86 in coupling 18 and connects to the lubricating oil source (not shown). Hole 88 is placed over another radial hole 81 in boring bar 41 which connects with axial hole 11.

To drill the bore of gun tube 3 one` endii's inserted in chuck 2 in theheadstock ofthe lathe. The other end of tube 3 is insertedy inthe hollow head of the cats head and centrally secured therein by the set screws I1. The jaws of chuck 2 are then tightened after centering the tube within the cats head 1. Drill 41 is next inserted in the tubular portion 43 of clamp holder 42 and lever 58 is pivoted in a clockwise direction so that the eccentric surface 63 will bear against clamp 54 thus securely holding boring bar 41 against rotation within the clamp holder. If desired a lathe steady rest can be placed around the forward end of boring bar 41 to provide additional support for boring bar 41 before and during drilling. l

Carriage 4 is then traversed along the bed l of the lathe until the end of drill 16 passes through bushing I4 and engages the end of gun tube 3. Oil is supplied through fitting 85 so that oil will pass through the axial hole 11 in drill rod 41 for lubricating drill point 16. The driving chuck 2 is then set in motion to revolve gun tube 3. The drill rod 41 is advanced into the work by the carriage 4, which is driven by the feed screw of the lathe. Drill 16 then continues to cut as long as the carriage is permitted to advance along the lathe bed l.

It is desired to point out that the drill rod carrier may be clamped about rod 41 in any desired position, thus enabling a lathe bed of comparatively short length to be utilized. For example, the drill rod carrier may be clamped approximately midway about drill rod 41 and the drill allowed to advance into the gun tube for this distance whereupon the lathe is stopped. The drill rod is unclamped and the carrier moved back so that the drill may be clamped near its end. The carriage 4 is then re-engaged to the feed screw and the drill permitted to cut to its full depth. It should be understood that the drill rod may be clamped in any intermediate position.

As previously mentioned the drill rod is mainly supported by the clamp holder. Additional support is furnished the drill rod 41 as it is brought into work engagement with the gun tube by the bushing I4 in the cats head. As the drill progresses into the tube the drill 16 loses the support of bushing i4. However, the drill is supported by the walls of the hole as the drill cuts its own path.

On occasion when a hard spot in the core of the gun tube is encountered by the drill the drill point will frequently freeze therein and unless some means is provided to permit the drill to unclamp and rotate with the workpiece the tremendous torque produced will cause the drill to break oir. This is overcome by the mechanical safety device already described which comprises the plunger 34 and the eccentric lever 58. Under normal operating conditions spring biased plunger 34 which is in engagement with the V-shaped notch 48 in clamp holder 42 will securely hold the boring bar 41 against rotation. However when the torque on boring bar 41 exceeds the normal boring torque due to freezing of the drill, the spring biased plunger 34 will be forced out of engagement with the V-shaped notch 4B in the clamp holder 42 and the clamp holder and boring bar together will be rotated approximately onequarter of a turn in a clockwise direction as viewed in Fig. 5, assisted by spring 69, until lever 58 strikes the adjustable stop 30.

Such movement will bring eccentric surface 63 of lever 58 out of camming engagement with clamp 54 and' thus umol-amp"boring`bar 41. The

drin will then rotateiwithguntube 3 within clamp holder 42 thus preventing breakage of the drill. y

The machine can then be' stopped as soon as this condition is noted and the drill freed from the gun tube.

It is apparent from the foregoing description that with lthis attachment lathes of comparatively short length'of bed may be readily utilized for deep hole drilling.` Furthermore in View cf the mechanical safety device which eliminates breakage of the drill conventional lathe equipment may be readily utilized without the addition of complicated elctrical'devices for the purposes of stopping the machine when the drill is frozen due to striking some obstruction in the bore.

rcIaim: 1 i p Y 1.4For` use in a machine tool having a longitudinal bed, a. toolV holder" comprising a bearing bracket arranged to be mountedonthe bed of the machine tool, a hollow bushing rotatably mounted in said bearing bracket and arranged to surround a tool shank, a clamp secured on said bushing and arranged to engage the tool shank, an operating member movably mounted on rsaid bushing and engageable with said clamp to tighten said clamp on the tool shank whereby the bushing may be'rigidly secured'to the tool shank, means for securing said bushing to said bearing bracket against relative rotation, means for releasing said last mentioned means operative upon application of a predetermined torque between said bushing and said bearing bracket, thereby producing rotation of said bushing relative to said bearing bracket, and a stop engageable by said operating member during such rotation of said bushing whereby said operating member is moved to a released position relative to said clamp.

2. For use in a machine tool having a longitudinal bed, a tool holder comprising a bearing bracket arranged to be mounted on the bed of the machine tool, a hollow bushing rotatably mounted in said bearing bracket and arranged to surround a tool shank, a split clamp secured on said bushing and arranged to engage the tool shank, a manually operated cam member movably mounted on said bushing and engageable with said split clamp to tighten said split clamp on the tool shank whereby the bushing may be rigidly secured to the tool shank, means for securing said bushing to said bearing bracket against relative rotation, means for releasing said last mentioned means operative upon application of a predetermined torque between said bushing and bearing bracket thereby producing rotation of said bushing relative to said bearing bracket, and a stop engageable by said cam member during such rotation of said bushing whereby said cam member is moved to a released position relative to said clamp. 1

3. For use in a machine tool having a longitudinal bed, a tool holder comprising a bearing bracket arranged to be mounted on the bed of the machine tool, a hollow bushing rotatably mounted in said bearing bracket and arranged to surround a tool shank, said bushing having a recess in a peripheral edge portion thereof, a clamp secured ing to said bearing bracket against relative roitation, said cam shaped end being constructed and arranged relative to the walls of said recess whereby a predetermined torque between said bushing and said bearing bracket forces said plunger out of engagement with said recess permitting said bushing to rotate relative to said bearing bracket, and a stop engageable by said operating member during such rotation of said bushing whereby said operating member is moved to a released position relative to said clamp.

4. For use in a machine tool having a longitudinal bed, a tool holder comprising a bearing bracket arranged to be mounted on the bed of the machine tool, a hollow bushing rotatably mounted in said bearing bracket and arranged to surround a tool shank, said bushing having a recess in a peripheral edge portion thereof, a split clamp secured on said bushing and arranged to engage the tool shank, a manually operated cam member 20 8 movably mounted on said bushing and engageable with said split clamp to tighten said split clamp on the tool shank whereby the bushing may be rigidly secured to the tool shank, a spring pressed plunger mounted in said bracket, said plunger having a cam shaped end engageable in saidv recess for securing said bushing to said bearing bracket against relative rotation, said cam shaped end being constructed and arranged relative to the walls of said recess whereby a predetermined torque between said bushing and said bearing bracket forces said plunger out of engagement with said recess permitting said bushing to rotate relative to said bearing bracket, and a stop engageable by said cam member during such rotation of said bushing whereby said cam member is moved to a released position relative to said clamp.

HERMAN C. GRAEBE. 

